This isn’t Iraq or Pakistan. It’s Mexico, which the U.S. government and a growing number of experts say is becoming one of the world’s biggest security risks.

The prospect that America’s southern neighbor could melt into lawlessness provides an unexpected challenge to President Obama’s government. In its latest report anticipating possible global security risks, the U.S. Joint Forces Command lumps Mexico and Pakistan together as being at risk of a “rapid and sudden collapse.”

“The Mexican possibility may seem less likely, but the government, its politicians, police and judicial infrastructure are all under sustained assault and pressure by criminal gangs and drug cartels,” the command said in the report, published Nov. 25.

“How that internal conflict turns out over the next several years will have a major impact on the stability of the Mexican state.”

The Justice Department said last month that Mexican gangs are the “biggest organized crime threat to the United States.” Outgoing National Security Adviser Stephen J. Hadley said last week that the worsening violence threatens Mexico’s democratic form of government.

Outgoing Homeland Security Secretary Michael Chertoff recently told the New York Times that he ordered additional border-security plans to be drawn up this summer as kidnappings and killings spilled into the United States.

The alarm is spreading to the private sector as well. Mexico - Latin America’s second-biggest economy and the United States’ third-biggest oil supplier - is one of the top 10 global risks for 2009 identified by the Eurasia Group, a New York-based consulting firm.

Mexico is brushing aside the U.S. concerns. Interior Secretary Fernando Gomez-Mont said on Jan. 14: “It seems inappropriate to me that you would call Mexico a security risk. There are problems in Mexico that are being dealt with, that we can continue to deal with, and that’s what we are doing.”

Still, Mr. Obama faces a dramatic turnaround compared with the last time a new U.S. president moved into the White House. When George W. Bush was elected in 2000, the nation of 110 million had just chosen Vicente Fox as president in its fairest election ever, had ended 71 years of one-party rule and was looking forward to a stable, democratic future.

Mr. Fox signaled readiness to take on the drug cartels but plunged them into a power vacuum by arresting their leaders, and gangs have been battling each other for territory ever since.

Felipe Calderon, who succeeded Mr. Fox in 2006, immediately dispatched troops across the country to try to regain control. However, soldiers and police are outgunned and outnumbered, and cartels have responded with unprecedented violence.

Mob murders doubled from 2007, taking more than 5,300 lives last year. Residents of the border cities of Juarez and Tijuana wake up each morning to find streets littered with mutilated, often headless bodies. Some victims are dumped outside schools. Most are just wrapped in a cheap blanket and tossed into an empty lot.

Warring cartels still control vast sections of Mexico, despite Mr. Calderon’s two-year crackdown, and have spawned an all-pervasive culture of violence. No one is immune.

Businesses have closed because they can’t afford to pay monthly extortion fees to local thugs. The rich have fled to the U.S. to avoid one of the world’s highest kidnapping rates. Many won’t leave their homes at night.

The government has launched an intensive housecleaning effort after high-level security officials were accused of being on the take from the Sinaloa cartel. In addition, several soldiers fighting the gangs were kidnapped, beheaded and dumped in southern Mexico last month with the warning: “For every one of mine that you kill, I will kill 10.”

Still, the U.S. government is extremely supportive of the Mexican president. It recently handed over $400 million in anti-drug aid. Mr. Obama met briefly with Mr. Calderon in Washington last week and promised to fight the illegal flow of U.S. weapons that arm the Mexican cartels.

Though fewer Americans are willing to drive across the border for margaritas and handicrafts, visitors are still flocking to other parts of Mexico. Also, the economy seems harder hit by the global crisis than by the growing violence.

The grim assessments from north of the border got wide play in the Mexican media but came as no surprise to people here. Many said the solution lies in getting the United States to give more help and let in more migrant workers who otherwise might turn to the drug trade to make a living.

Otherwise, the drug wars will spill ever more heavily into the United States, said Manuel Infante, an architect.

“There is a wave of barbarity that is heading toward the U.S.,” he said. “We are an uncomfortable neighbor.”